Process for refining sulphurcontaining hydrocarbon oils



Sept. 28, 1943. 2,330,735

CQNTAINING HYDRocARBoN oILs Filed Jan. 24, 1942 H. C. PAULSEN PROCESS FOR REFINING SULPHUR- $54036 N5 om..

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.ll-Illll Y Patented Sept. 28, 1943 PROCESS Foa REFINING SULPHUR- ooN'rAiNING HroaocARBoN oILs Henry CfPaulsenLElizabeth, N.J., assignor to-` Standard AOil Development Company, a corporation of Delaware Application January 24, 1942, Serial No. 428,048

4 Claims.

This invention relates toa method for sweetening sour hydrocarbon oils,'such as gasoline, kerosene, and heating oils, more particularly, for removing objectionableodoriferous and corrosive sulphur components from such oils by treatment with an alkaline aqueous solution containing cuprio hydroxide.

The most common sweetening'method is the doctor treatment,'which consists in treating a sour oil with added sulphur and a caustic solution of sodium plumbite to convert mercaptans, whichV render the oil sour, into alkyl sulphides. Althoughthe doctor treatment is an effective sweetening process, it has severalvserious disadvantages. In `actual practice, itgenerally` involves the use of added free sulphurto accelerate and complete thereaction (disulphide and lead sulphide formation). `:This practice leads to an increase rather than a reduction in the ltotal sulphur content of the oil,` thus causing sweetened products to be corrosive, and tending to make gasoline fuels have a lower anti-knock value, particularly less response to lead alkyl anti-knock agents.

A general object of this invention is to provide a sweeteningtreatment which is satisfactory for various types of petroleum oil distillates and which does not require an addition of sulphur. Another object is to provide a refining process capable of effectively reducing the total sulphur content of an oil by removal of mercaptans and corrosive sulphur.

aqueous sodium hydroxide `solution `containing relatively small amounts of cupric hydroxide and lead sulphide, in the presence or absence of added air or oxygen, then separating from the oil the spent treating solution and precipitated sulphurcontaining reaction products. Instead of using sodium hydroxide, other closely related bases, suchas potassium hydroxide or alkali metal earth hydroxides may be employed in the aqueous solution, but sodium hydroxide is preferred.

A suitable concentration of the sodium hydroxide in the treating solution comes in the rangeof about 10 to 30% by Weight. Significantly,4 the, proportion of cupric `hydroxide may be rather small for satisfactory results, as, for example, about 1 to 10%. The lead sulphide or heavymetal compound, likewise, need be used in only very small amounts, generally, in a smaller weight proportion than the cupric hydroxide, e. g., about 0.1 to 5%. i

Whileit has been observedthat cupric hydroxide in the alkaline solution without lead sul- A further object is to provide Ia method of treatment which is accomplished expeditiously and with curtailment in the expense of sweetening chemicals.

I have found that an alkaline or alkali metal hydroxide solution containing cupric hydroxide phide or other heavy metal sulphide may be substantially as eiective in purifying a sour and corrosive hydrocarbon distillate as with the lead sulphide, it` was noted that a small amount of the heavy metal sulphide very advantageously favored the rate of settling and improved the regeneration of the spent treating agent. The regeneration involves oxidation as, for example, by air blowing, but theheavy metal sulphide in serving to accelerate thej regeneration may be allowed to remain unchanged While the decomposition products of the spent `cupric hydroxide are oxidized.

To prepare `the treating agent, cupric hydroxide may be formed very simply by admixing cupric acts as an efficient sw-eetening agent without may be employed but with different vdegrees of eff fectveness as, for example, cadmium sulphide or cobaltic sulphide, and the .like, the 'preferred heavy metal sulphides being highly 'stable and insoluble in alkali sulphides or alkalinesolutions.

. In a preferred specific embodiment, theprocess of this invention is conducted by treating .a `sour or sulphur-containing hydrocarbon oil Wuhan chloride with an aqueous sodium hydroxide solutionl or similar basic solution from which the cupric hydroxide is4 precipitated. `The precipitated cupric hydroxide may be separatedfrorn the reaction solution and be washed free of chloride salts before being added to the alkaline solution to be used as a treating agent. However, since thearnount of cupric hydroxide employed is fairly small for the present process, the 4amount ofchloride salts formedV in precipitating the cupric hydroxide'is not very detrimental, so that the cupricjhydroxide may `be'precipitated directly in the alkalinetreating solution. Thelead sulphide maybe preformed for addition to the treating agent in any convenient manner, forexample, it may be formed by passing hydrogen sulphide into an aqueous solution of a lead'salt, or by reacting plumbite withsodiumlsulphide A partial regeneration of the treating agent may be effected during the sweetening operation t by introducing controlled Iamounts of air into the treating vessel, but itis preferred to have a complete regeneration of the spent treating agent after it is separated from the sweetened oil product.

The process is adapted for either batchv of clon-A tinuous operation, the latter being preferred in commercial practice. The process may loe carried out in conventional refining equipment like f that used in a doctor treatment. A suitable for-mwy l of apparatus for plant practice ofthey invention is illustrated diagrammatically in the accompanying drawing which shows an elevational view of the apparatus with parts in cross section.

Referring to the drawing, a sour hydrocarbon distillate is introduced into itheunit through `feed inlet line l being intimately commingled with the alkaline treating agent from line 2 in anbrice' mixing device 3.v The mixture from theoriirce mixer is passed by` line` 4 into a settlingAk tank 5v wherein a portion or 'all yof the aqueous treating agent is separated-,from the oilby gravity and 1so that separated yagentmay, be withdrawn from f settlers maybe passed by line ll to a regeneration zone wherein the spent reagent is blown with air under controlled conditions, e. g., under ordinary or elevated pressures at about 50 F. t'o 1`40 -tol regenerate the cupric hydroxidek and alkaline agent. With the heavy metal sulphide -p'resent in the reagent, the oxidation in the regenerato assist the cupric hydroxide treatment for the most part remain unaiected in their composition during the sweetening treatment and the regenerijation; and accordingly, they may be regarded as being circulatedwithout undergoing substantial change. The following specic examples on the l treatrn'ent of a sour `Icracked gasoline will serve to illustrate how the invention is practiced and advantages derived therefrom.

' ,Example A sweetenin-g' vagent `(500 vm1.) was made by adding about f28 gramsioi cupric hydroxide to an aqueous. solution containing about l141 by Yweight of sodium hydroxide, Aand approximately 5 grams of lead sulphide were also added tothe solution. About 10% :by volume of this mixture was added to a sour cracked gasoline, stock and agitated therewith at about 80 E?. for about 3 minutes. The treated gasoline was then separatedfrom the aqueous treating agent,-and-'it was found to have a very satisfactoryreduction -in sulphurv content with substantially lcomplete elimination of Amercaptans Aand sulphur .corrosive Yto copper.

`Infurther studies of this treating method, -comparative tests were made 4on samples t'of a sour cracked gasoline stockwith vari-ations in the treating agents but under'comparative conditions. The results Yare summarized. 1in the` following table:

Operation: i

V,ol. per cent treating agent ,1 0.; 10` 10 350 gitatiogLF minutes.. 8g `83 j Doctgrtest Passy Doesnot. Does not pass Mercaptan sulphur, mg;/l00m1 25 Nil Rcactiveksulphur, mg./l 00 ,n1l 30.5 v llil Total sulphur, wt. per cent.` 0.186,0.184 0.159

tion may vbe controlled to avoid substantialloxidation of the heavy metal sulphide, for, in general, itis preferred rio-tto transform the heavy metal sulphide,v such as the lead sulphide, i'n'to the oxide, siric'ein 'the -oxidized form, the lead oxide, for example, tends 'to alter the desired treating reaction, i. e., tends toimpart Athe character of adoctortreatment. 4 f l 't The sweetened foil separated from thespent treating agent is then passed from ythe ''rial 'settler line vI'2int`o anA ori'ce mixerto be intimately contacted Wvth. Win/'ash (water, 'A then V'S ASeparated frm'th-e Was'hwater by beilgfsft'ffrh theorice mixer i3 tl'irugh line Tfirto tlief lWashsettler f5, Th'iuS-d'wfh WatellS Yse!Lttd. in the Settlr (Sironithe Washed ndsvveeterie 1t'reatrnentstver'e'ri'afde 'in the presence of iut 'gen' gas. The 'data from the' 'compared sweetenin'g vpro'cdir'es 4irdialt'ed that "the cupric hydrdde 'agent 'arid' "cupric hydroxide-'lead sulphide 'agent completely ved 'merc'aptan ysui-- priur, reattive "sulphur corrosrve 'to topper, and produced satisfactory sweet 'stocks awarding :to trie' 'doft'or test. However, 'itwasindtedftrrat 'with 'L sent, :tliejusedwcupric hy'- d'rsiide agent "seiner ed'ffrdm the swdeterred jon eli-ably raster and the sweet-erleben was as'ly 'wa ter-wasned"than in.` the -ct'her treatments. Furtherrrioiejthe cupric'hydroxide'- lead "su'ipr'iide treating agent was found to be tcul'arly noticeable in treating cracked gasoline stocks which are diicult to sweeten owing to their high sulphur and mercaptan content.

With the high concentration of alkali and with the heavy metal sulphide present, the treatedoil is kept fairly free of dissolved copper salts which tend to be detrimental to oxidation resistance of the oil, but, if desired, a small lamount of an arsenite, e. g., sodium arsenite, may be used in washing the sweetened product to insure elimination of copper compounds from the oil, or any other effective measure for removal of copper may be used.

The exact treating period, proportions and ternperature conditions for rening depend on the nature of the oil stock which is to be refined. It was indicated that from 5% to 30% by volume of the treating agent, a contact time ranging from l minute to 15 minutes, and a temperature ranging from atmospheric temperature up to 100 F. were adequate to satisfactorily sweeten sour distillates.

It is to be understood that the foregoing examples are given only for the purpose of illustration and that various changes may be made which come within the scope of the invention `as defined in the appended claims.

with an aqueous solution containing a caustic alkali, a minor proportion of cupric hydroxide, and a small amount of a sulphide of a multivalent heavy metal in suspension.

2. In a continuous process of sweetening sour petroleum distillates, the improvement which comprises intimately contacting sour distillates with an aqueous sodium hydroxide solution containing a, minor amount of cupric hydroxide and lead sulphide until a substantial reduction in the sulphur content of the distillate is obtained,

separating the distillate of reduced sulphur conl 4. In a process of refining a sour cracked naphtha containing corrosive sulphur, the improvernent which comprises reacting sulphur compounds in the naphtha with cupric hydroxide contained in an alkaline aqueous solution and in the presence of a heavy metal sulphide suspended in said solution.

HENRY C. PAULSEN. 

